Hydraulic control actuator

ABSTRACT

A hydraulic control actuator in the form of a compact mechanism having a long, maintenance-free service life. The actuator comprises a reservoir portion for retaining a supply of actuating liquid and a bowl-type pump disposed above said reservoir portion and rotatable about a generally vertical axis. The pump includes a casing which produces a rotating liquid ring therein upon rotation of the casing. Means coacts with the casing and extends downwardly therefrom below the top surface of the liquid in the reservoir portion, wherein actuating liquid is drawn upwardly from the reservoir portion into the casing in a self priming operation upon rotation of the casing. Scoop means is provided interiorly of the casing which communicates with passageway means for directing in a precisely controlled manner the pressurized liquid from the rotating liquid ring to a liquid power control mechanism, such as, for instance, a reciprocal motor unit, which in turn is adapted to control a hydraulic controller, such as, for instance, a valve or other mechanism. The actuator is characterized by being capable of providing precise, highly stabilized control and being of simple construction, requiring no seals between relative movable parts, thus eliminating wear and maintenance problems.

United States Patent [1 1 Schweitzer [451 July 3, 1973 HYDRAULIC CONTROL ACTUATOR [22] Filed: Nov. 8, 1971 [21] Appl. No.: 196,625

[52] US. Cl 60/325, 60/477, 415/89 [51] Int. Cl FlSb 15/18 [58] Field of Search, 60/52 T, 52 US, 325,

[56] References Cited UNITED STATES PATENTS 3,098,358 7/1963 Paschke 60/52 T 3,374,747 3/1968 King et al. .l 415/89 FOREIGN PATENTS OR APPLICATIONS 372,383 3/1923 Germany 60/477 Primary Examiner-Edgar W. Geoghegan AttorneyRobert J. Fetzer 571 ABSTRACT A hydraulic control actuator in the form of a compact mechanism having a long, maintenance-free service life. The actuator comprises a reservoir portion for retaining a supply of actuating liquid and a bowl-type pump disposed above said reservoir portion and rotatable about a generally vertical axis. The pump includes a casing which produces a rotating liquid ring therein upon rotation of the casing. Means coacts with the easing and extends downwardly therefrom below the top surface of the liquid in the reservoir portion, wherein actuating liquid is drawn upwardly from the reservoir portion into the casing in a self priming operation upon rotation of the casing. Scoop means is provided interiorly of the casing which communicates with passageway means for directing in a precisely controlled manner the pressurized liquidfrom the rotating liquid ring to a liquid power control mechanism, such as, for instance, a reciprocal motor unit, which in turn is adapted to control a hydraulic controller, such as, for instance, a valve or other mechanism. The actuator is characterized by being capable of providing precise, highly stabilized control and being of simple construction, requiring no seals between relative movable parts, thus-eliminating wear and maintenance problems.

19 Claims, 23 Drawing Figures PAIENTEDJuL 3 I975 SHEEI 1 0F 4 INVENTOR. 421. 0. Sl/WE/TZEZ HYDRAULIC CONTROL ACTUATOR This invention relates in general to hydraulic control actuators of the type which include a bowl-type pump, and more particularly to a hydraulic control actuator which is of compact construction, and which embodies no frictional. relatively movable parts necessitating seals between the parts, thus resulting in a long wearing, maintenance-free mechanism possessing precise hydraulic control characteristics.

BACKGROUND OF THE INVENTION Many types of hydraulic actuators for controlling the actuation of a valve or other fluid control mechanism are known in the art. However, most of'these prior art arrangements are relatively complex and thus relatively expensive, or else they do not operate satisfactorily to accomplish the desired purpose. Usually they comprise too many relatively movable parts, necessitating seals and the like between the relatively movable parts, or else the mechanism is too bulky for general use and comprises too many parts which wear out relatively rapidly.

SUMMARY OF THE INVENTION The invention provides a hydraulic control actuator which is relatively compact in size, possesses relatively few parts and does not wear out rapidly, and requires relatively little maintenance, and wherein the mechanism includes a reservoir portion disposed in close relationship to the self priming pumping portion of the actuator, and wherein precise, stabilized control of the hydraulic actuating liquid is realized.

Accordingly, itis anobject of the invention to provide a novel hydraulic control actuator mechanism.

7 Anotherobject of the invention is to provide a hydraulic control actuator mechanism which includes a reservoir portion and a bowl-type pumping portion dis-' posed in closely associated relation, and wherein the casing of the pumping portion is rotatable about'a generally vertical axis passing through the underlying reservoir portion.

Another object of the invention is to provide a hydraulic control actuator mechanism of the above specified type which includes self priming means, for causing the liquid from the underlying reservoir portion to flow into the casing of the pumping portion, upon rotation of the pumping casing and initially causing air to flow from the casing back to reservoir.

A still further object of the invention is to provide a hydraulic control actuator of the aforedescribed type, wherein the casing includes a tubular-like member depending therefrom to a position below the level of the liquid in the reservoir portion, and which tubular member has passageway means therein for feeding fluid from the reservoir portion to the casing to form the rotating liquid ring in the casing during rotation thereof, and also has passageway means therein for initially 'exhausting air from the casing back to the reservoir, for providing the aforementioned self priming means for. the pumping section of the actuator mechanism, and

wherein no seals between relatively movable parts of BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is' a sectioned, elevational view of a hydraulic control actuator formed in accordance with the invention, and wherein the actuator is adapted for use with a double acting liquid powered motor unit for controlling a valve mechanism or other fluid controller;

FIG. 2 is a fragmentary, sectionalview of an actuator similar to that of FIG. 1, but wherein the actuator is shown for use with a single acting motor unit rather than a double acting unit as illustrated in FIG. 1;

FIG. 3 is a fragmentary, sectional, elevational view showing the return line from the aforementioned single acting motor unit mechanism, for returning the liquid from the non-actuated side of the piston thereof back to reservoir; Y 7

FIG. 4 is an enlarged sectional view taken generally along the plane of line 4-4 of FIG. 2, looking in the direction of the arrows;

- FIG. 5 is an enlarged, sectional, elevational view taken generally along the plane of line 55 of FIG. 2 looking in the direction of the arrows, and illustrating the valving control for controlling the application of the pressurized liquid from the pumping portion of the FIGS. 8, 9 and 10 are diagrammatic, sectional views of the valving mechanism for coupling the egress of actuating liquid from the pumping section to one or the other end of a double acting motorunit, such as the type illustrated in FIG. 1;

FIGS. 11, 12, and 13 are diagrammatic, sectional illustrations of valving mechanism for use in controlling a single acting motor unit, 'and is the general type shown, for instance, in FIGS. 2 and 5;

FIG. 14 is a generally diagrammatic, sectional, fragmentary illustration of a further embodiment of actuator whichutilizes an elongated tubular supply member coacting in depending relation with the rotatable casing of the pumping portion, and wherein the priming means for the supply member comprises a laterally projecting hollow stem communicating'via a vertical passageway with the interior of the. pumpcasing;

FIGS. 15, l6'an'd 17 are diagrammatic, sectional illustrations of a further valving. arrangement for controlling the flow of the actuating liquid from the pumping .section to one end of a single actingmotor unit of the actuator mechanism;

FIG. 18 is a top plan, diagrammatic illustration of a further embodiment of scoop tube utilizable with the actuator mechanism;'

FIG. 19 is a diagrammatic, top plan illustration of a rotatable casing of an actuator providing a rotating liquid ring, and wherein scoop tube means is provided extending in opposite directions so that rotation of the casing in either direction provides for a flow of actuating liquid from the rotating liquid ring to the motor unit that is to be actuated;

FIG. 20 is a sectional view taken generally along the plane of line 2020 of FIG. 19 looking in the direction of the arrows;

FIG. 21 is a perspective diagrammatic illustration of the aforementioned valving lever and feedback mechanism, for precisely and smoothly controlling the application of liquid from the pumping portion of the actuator to the reciprocal motor unit portion; and

FIG. 22 is a sectional view taken generally along the plane of line 22-22 of FIG. 14 looking in the direction of the arrows;

FIG. 23 is a diagrammatic illustration of a surge chamber added to the supply passage of, for instance, the FIGS. 15-17 arrangement.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIG. 1, there is shown a hydraulic control actuator mechanism 10 comprising a reservoir portion 12 adapted for containing a quantity of liquid 14, such as water, and a pumping portion 16, disposed above the reservoir portion 12, and rotatable about a generally vertical axis. Pumping portion 16 comprises a casing 18 of a bowl-type pump which has an upstanding portion 20 formed thereon adapted for connection to shaft 22 of a power unit, such as an electric motor 24, thus providing for high speed rotation of casing 18 of pumping unit 16, about a generally vertical axis.

Depending from the casing and attached thereto, as by means of threaded fasteners 26, is an intake or supply member 28, which in the embodiment illustrated is of inverted truncated conical-like configuration, with the lower end of the supply member 28 being adapted to always be disposed below the surface L of the liquid in the reservoir portion 12 during operation of the actuator. Supply member 28 has a stepped exterior configuration, as can be seen in FIG. 1, for the purpose of aiding in preventing turbulence of the liquid in the reservoir 12, during rotation of the casing 18 and attached member 28.

Obliquely arranged supply passages 30 extend from the underside of member 28 to the top side thereof, wherein the passages communicate with the interior of the pump casing 18. The central portion of member '28 is provided with an inverted truncated conical shaped opening 32, which at its upper end communicates with the interior of the pump casing 18 and at its lower end communicates or opens onto the undersurface of member 28. A laterally extending passageway 32a disposed adjacent the lower end of member 28 communicates opening 32 with the lateral exterior of member 28.

Extending through opening 32 axially of the casing 18, is a discharge column or tube 34, which is stationary with respect to the rotatable casing 18. Coupled to the column 34 and extending laterally therefrom is a scoop tube 36 which is adapted to scoop liquid under pressure from the rotating liquid ring in the casing 18 during rotation of the latter, and pass it via the tube 36 and discharge column 34, and via tubing 38, to valving mechanism 40. Mechanism 40 which will be hereinafter discussed in greater detail, is adapted to control to which end of the double acting motor unit 42 that the pressurized liquid from the pumping portion 16, will be applied. Movement of the piston and associated piston rod 44 of hydraulic powered unit 42, is adapted to control some control mechanism, such as a flow control valve in a hydraulic circuit, or some other control mechanism, in a precise and smooth manner.

Aforementioned lateral passage 32a serves as a self priming means for stem member 28. During rotation of the casing 18 and thus rotation of the attached member 28, a vacuum is formed at the outer end of the passage 32a, causing air to be initially drawn down from the interior of the casing 18 through the central opening 32, and out lateral passage 32a, where it escapes into the reservoir portion 12, causing the liquid from the reservoir 12 to be supplied via the oblique openings 30 in member 28, to the interior of the casing 18, to form a rotating liquid ring during rotation of the sing.

Supply column 34 and associated scoop tube 36 are stationarily supported as by means of fasteners 42 on a rigid plate support member 44, which in turn is supported by means of spaced rigid hangers 46 to upper structure 48 of the actuator housing. Plate 44 which may be of circular configuration in plan to conform to the circular configuration of the reservoir portion 12, has an opening 50 therethrough through which the aforementioned supply column 34 extends into coaction with the interior of rotary casing 18. As can be seen from FIG. 1, the supply passages 30 in stem member 28 overly the opening 50, and thus the liquid in the reservoir portion can readily move from beneath the plate 44 area up through the passages 30 and into the casing during rotation of the latter. Moreover, member 28 on its underside preferably just barely engages the top surface of the plate 44, thus sealing the underside of tapered opening 32 in member 28, and causing the air withdrawn from the interior of the casing 18 to pass laterally out the laterally extending passage 32a in member 28. As can be seen, the plate 44 prevents any turbulence and foaming that may be produced by rotary movement of the casing and attached member 28, from affecting the liquid which is drawn up from the reservoir from beneath the plate into the casing, thus insuring positive and smooth operation of the hydraulic powered motor unit 42 or other controller to which the actuator is coupled.

The aforementioned valving mechanism 40 may include a pivot arm or pivot plate 52 (FIGS. 1 and 21) which is fulcrumed or pivoted as at 56 at a plurality of laterally spaced points (FIG. 21). Pivot arm 52 has a valve head portion 58 (FIGS. 8 to 10) which is adapted to coact with the emission end port of aforementioned supply tube 38, to direct the liquid from the tube 38 coming from the rotating liquid ring in casing 18, to one or the other of feed tubes 60, 60a, which feed liquid to one or the other end of the aforementioned reciprocal motor unit 42.

Each feed tube 60, 60a has an entry port opening 62 or 62a therein, and when the valve head portion 58 coacts in predetermined relationship with one or the other of the port openings 62, 62a, the pressurized liquid in supply tube 38 from the casing is directed to the proper feed passageway 60 or 60a, to thereby apply the pressurized actuating liquid to the selected end of the piston 44 to cause actuation thereof. Head 58 of valving mechanism 40 preferably includes a cylindrically concaved surface 66 (FIGS. 8 to 10) which coacts with the supply passage 38 and receivingports 62, 62a to effectively direct the liquid flowto one or the other of the feed passages 60, 60a or to exhaust back to reservoir.

As can be seen in FIG. 9, when the head portion 58 of the valving mechanism is in the position illustrated, the liquid from supply passage 38 flows to feed passage 60 thereby causing movement of the piston and piston rod 44 of motor unit 42 upwardly (with regard to FIG. 1). Referring to FIG. 10, when the head portion 58 coacts with the supply passage 38 and feed passage 60a in the manner illustrated, the liquid coming from the pumping section 16 is directed to the feed passage 60a, thereby causing the piston and associated piston rod 44 .of motor unit 42 to move downwardly (with regard to by means of the force coil 67 which is coupled as by means of linkage 68 to the pivot arm 52, and which, when actuated, causes the pivot arm 52 to pivot about its fulcrum points 56 and with respect to the stationary support plate 44, to cause movement of the valve head into coaction with the selected of the feed passages 60, 60a. When the valving head 58 is in the position illustrated, for instance, in FIG. 8 flow from the supply passage 38 is of course released to the reservoir from either side of the head portion 58.

Valving head 58 being of a comparatively compact, small size cross section can be moved freely with respect to the valving passageways 38, 60, 60a, to provide forsmooth operation of the valving mechanism during actuation of the latter.

The pivot plate 52 on theother side of pivot points 56 may be coupled as by means of linkage 70, to the support cover 48 of the actuator and as at 72, and may also be coupled to feedback spring mechanism 74 which is coupled via arm structure 76 to the piston rod and associated piston of motor unit 42, to thus provide feedback control of the actuator mechanism. Thus movement of the piston and associated piston rod 44 of the motor unit 42 is transmitted via the feedback 74 to the valving mechanism 40 for automatically compensating for movement of the motor unit.

As can be seen in FIG. 1 the electrical lines to the power unit 2.4 for rotating the pump section, and the power line to the force coil 67 can be supplied via conduit 80 extending into the actuator housing.

Referring now to FIG. 2, there is shown a further embodiment of the actuator which is adapted for coupling to a single acting spring return motor unit (not shown) rather than the double acting type of motor unit 42 ilpivot arm or plate 52' in the same general manner asthat of the FIG. 1 embodiment, including head portion 58 (FIG. 2). Head portion 58' of the valving mechanism 40 controls the flow of pressurized liquid to thesupply line 60' from whence it is applied to the piston and associated piston rod of the single acting motor unit, when the head portion 58' is in the position illustrated in FIG. 5 closing the exit opening 81 from the supply line 38. However, when the head portion 58 moves as shown, for instance, in FIGS. 12 and 13, to open the exit port 81 in the valving mechanism 40, the liquid from the pumping portion flows out the exit passage and thus is not applied to the hydraulic powered controller (e.g. the reciprocal motor unit). The liquid behind the piston of the single acting motor unit may be directed back to the reservoir via passage 60a (FIG.

5) whence it is applied to the reservoir 12 below the support plate 44'. The motor unit can be of the spring return type so that the piston is automatically returned when the pressure applied to one side of the piston is removed. It will be seen that the head portion 58 of the valving mechanism being of small cross section glides readily and smoothly relative to the exit passe 81, to control the flow of actuating liquid from the pumping section of the actuator to the motor unit.

As can be seen in FIGS. 3 and 5, the return line from the single acting motor unit preferably terminates adjacent a side of the reservoir portion 12' and below the shield plate 44'. This aids in preventing turbulence in the liquid being drawn up into the rotating casing 18' from below plate 44'.

Referring now to FIG. 7, there is shown a top plan view of scoop tube 36 or 36' which is generally tapered in the lengthwise direction thereof toward the distal or inlet end wherein the inlet port 83 is located. In transverse cross section the scoop tube is preferably of a generally tear drop or bi-convex configuration, for facilitating the flow of liquid around the body of the scoop tube during rotation of the casing 18.

FIG. 18 shows a modification of scoop tube 36a wherein other ports 83 in addition to the end port 83a are provided in spaced relation along the lengthwise extent of the scoop tube, and with lightly spring biased valve means 86 coacting with each of the ports 83' for initial closing the ports 83'. Upon application of pressure by the'rotating liquid ring in the rotating casing being applied against the valve means 86, the latter are caused to open, as illustrated, permitting pressurized liquid to further flow through the ports 83' in addition to the flow of liquid through the entry. port 83a, and

' thus supply greater pressurized flow of liquid to the column passage 34, whereby more rapid movement of the hydraulic powered control mechanism (e.g. 42) is accomplished. When motor unit 42 reaches a stopped or slowed down position, the pressure in column passage 34 and in the scoop tube builds up to cause closure of ports 83', thereby automatically reducing liquid intake into the scoop tube.

Referring now to FIG. 14, there is shown a further embodiment of actuator wherein the stem' member 28" comprises a cylindrical structure formed of a hollow outer cylinder 88 and with a much smaller diameter cylindrical tube 90 being secured to the interior thereof and passing therethrough. Cylinder 90 has a laterally extending tuber portion 92 communicating therewith which isobliquely arranged on its distal end, as at 94 (FIG. 22). Member 28" may be coupled axially to the casing 18" by means of the threaded collar portion 96 (FIG. 14). Y

Rotation of the stem member 28" with rotation of the casing 18" causes a suction to be formed at the outer end of the laterally projecting tuber portion 92 and thus air is drawn. out of the interior of the casing .during initial rotation thereof, to self prime'the casing and cause the liquid from the reservoir to flow upwardly through the main cylindrical portion 88 of member 28" into the casing, to form the rotating liquid ringv As can be seen, the stem member 28" extends through the opening 50" in the support plate 44" so that liquid can be readily drawn up from the underside of the plate 44" through the member 28" and into the rotatable casing.

Vertically extending laterally spaced vanes 98 (FIG. 14) oriented generally radially outwardly from the stem member 28" may be provided for stabilizing the liquid during rotation of the casing and associated member 28". A continuous splash guard 100 may be provided removable attached to the tops of the vanes 98, for further aiding in preventing turbulence and foaming of the liquid in the reservoir portion 12".

FIGS. 15 through 17 illustrate a valving arrangement 40" for a single acting spring return motor unit wherein stops 101, 101a are provided adjacent the ends of the range of travel of the valve head member 58' for limiting of travel of the head member with respect to the supply passage 38". In FIG. 15, the hold position, the pressurized liquid coming through supply passage 38" from the pumping section is blocked while the actuating liquid in the feed passage 60" to the single acting motor unit is likewise blocked. The motor 24 driving the pumping portion 16 thus automatically requires less power in the hold position of the valving, and the motor if it is for instance an electric induction motor, would tend to speed up. In FIG. 16 the liquid from the supply passage 38" is transmitted via the concave seat 66" in head 58" to the feed passage 60" leading to the hydraulic powered single acting motor unit, to cause actuation of such motor unit. In such position the head 58" engages stop 101. In FIG. 17 the pressurized actuating liquid from the supply passage 38" is again blocked whilev the liquid in feed line 60" going to the actuated side of the motor unit is open to reservoir via the concave seat 66" in head 58''. In the latter instance, as can be seen, the head is engaged with the stop 101a to prevent further movement of the head and properly positioned the latter with respect to the passages.

Referring now to FIG. 19, there is illustrated diagrammatically a pumping portion 16 for an actuator of the type of the invention wherein the scoop 36" has scoop openings adjacent its distal end which are directed in opposite directions in the rotatable casing 18", with the scoop tube being divided lengthwise thereof as at 102 so as to provide plural scoop, tube pas-' sages. It will be seen that the casing 18" of the pumping section is adapted to be rotated in either rotary direction and therefore cause scooping of actuating liquid from the rotating liquid ring in either of its rotary directions, for supplying pressurized liquid to a hydraulic powered controller. By coupling each of the scoop tube passages to an opposite end of the hydraulic powered controller, such as, for instance, a double acting reciprocal, motor unit, the active scoop tubepassage (i.e. the one facing opposite to the-direction of rotation of casing 18") passes pressurized liquid to the associated end of the controller for actuation of the latter, while the other scoop tube passage (i.e. the one facing in the direction of rotation of casing 18") returns liquid from the associated end-of the controller back'to the casing 18". v

There is no limit on the type of liquid useable in the actuator mechanism. However, the liquid is preferably of low viscosity, with water being entirely suitable. Other liquids having necessary or desirable characteristics can however be substituted for water, such as, for instance, liquids having greater freezing and/or boiling points, etc.

While the valving arrangement shown in FIGS. 8 10 is not illustrated as being of the hold type, for completely blocking the egress of actuating fluid from the pumping portion passage 38, it will be understood that it could be so arranged and in the manner as shown for instance, in FIG. 15.

FIG. 23 illustrates a surge tank 104 in supply line 38" from the pump section. When the valve head 58" is in hold position, the liquid from the pump builds up pressure in tank 104. When the valve head is moved or opened so as to provide communication of supply line 38" with feed passage 60" (FIG. 16) an additional flow of liquid under pressure from the tank 104 is applied to passage 60". Valve mechanism 106 may be provided on the tank 104 to permit entry of air into the tank when the pump is not operating.

From the foregoing discussion and the accompanying drawings it will be seen that the invention provides a novel hydraulic actuator for precisely and smooth controlling a hydraulic powered controller, and wherein the actuator comprises a reservoir portion and a rotatable pumping portion disposed above'the reservoir portion with the pumping portion including a rotatable casing providing a rotating liquid ring and having a supply stern portion extending downwardly into the reservoir portion for supplying actuating liquid from the reservoir portion to the casing, and which includes self priming means for priming the pumping portion together with a novel arrangement of valving mechanism for controlling the flow of pressurized liquid to the hydraulic powered controller.

The terms and expressions which have been used are used as terms of description and not of limitation, and there is no intention in the use of such terms and ex-, pressions of excluding any equivalents of any of the features shown or described, or portions thereof, and it is recognized that various modifications are possible within the scope of the invention claimed.

What is claimed is:

1. In a hydraulic actuator comprising a reservoir portion for storing actuating liquid, a bowl-type pump ineluding a rotary casing adapted for receiving actuating liquid therein disposed above said reservoir portion, said casing being rotatable about a generally vertical axis and including means adapted for coupling to power means for rotating said casing to produce a rotating liquid ring of the actuating fluid in said casing, scoop means disposed interiorly of said casing for removing liquid from the rotating liquid ring during rotation of said casing, means coacting with said scoop means for transmission of the liquid from said scoop means to a hydraulic powered control mechanism, means coacting with said casing and extending downwardly therefrom into said reservoir portion for supplying liquid from the reservoir portion into said casing for forming said liquid ring, the last mentioned means including means for exhausting air from said casing during rotation thereof. and providing for self-priming of said pump. 7

2. An actuator in accordance with claim 1 wherein said last mentioned means iscircular in horizontal cross section and is d etachably attached to said casing.

3. An actuator in accordance with. claim lwherein said last mentioned means is in the form of an inverted truncated conical-like member secured to said casing egress of air from said casing during initial rotation of the latter. I

4. An actuator in accordance .with claim 1 wherein said last mentioned means comprises an elongated member secured to the underside of said casing substantially axially thereof and rotatable therewith, said member having passageway means thereinextending generally lengthwise thereof from the underside thereof into communication with the interior of said casing, for the movement of actuating liquid from said reservoir portion upwardly into said passageway means and thence into the casing upon rotation thereof, said priming means comprising other passageway means in of liquid from said scoop means to and from said hydraulic powered control mechanism.

10. An actuator in accordance with claim 9 wherein said conduitmeans is disposed in said reservoir portion,

power means coupled tosaid pivot arm for driving said valve head in a predet'ermfined direction to'select ively control the flow of liquidfrom said scoop means to said conduit means, and feedbackmeans coacting with said valve member andjwith said hydraulic powered control mechanism, for maintaining stability in the operation of said valve member.

11. An actuator in accordance with claim 10 wherein Y the last mentioned power means comprises an electrical force coil.

12. An actuator in accordance with claim 9 wherein said stationary support includes agenerally horizontally oriented plate disposed in said reservoir portion above said valve member for protecting the valve member and associated entry port of said conduit means from foaming of liquid in said reservoir portion.

13. An actuator-in accordance with claim 12 wherein said conduit means comprises a pair of separate conduits connecting said valve member with the hydraulic powered control mechanism, each of said conduits insaid member extending from communication with the casing downwardly to open laterally of said member and adapted to open below the level of the actuating. liquid in said reservoir portion, whereby air in said casing will be initially discharged through the last mentioned passageway means during initial rotation of said casing to permit actuatingliquid to be drawn from said reservoir portion through the first mentioned passageway means in said member into said casing to form the rotating liquid ring.

5. An actuator in accordance with claim 4 including stationary means coacting with the underside of said member, said stationary means comprising a generally horizontally oriented plate mounted in said reservoir portion and engaging the underside of said member, said plate having an opening therein directly communicating the first mentioned passageway means with the area of said reservoir portion disposed below said plate.

- -6. An actuator in accordance with claim 1 including a power unit operativelycoupled to said casing for causing rotation thereof, and means mounting said power unit above said casing.

7. An actuator in accordance with claim 1 wherein said priming means includes a hollow stem projecting laterally of said last mentioned means for creating a vacuum during rotation of said casing and last men- .tioned means for initially drawing air from said easing into said reservoir portion during rotation of said casing. Y

8. An actuator in accordance with claim 1 wherein said means coacting with said scoop means comprises a movable valve memberoperable for directing liquid from said scoop means to a predetermined transmission path to the hydrauliclpower-control mechanism,

9. An actuator in accordance with claim 8 wherein said valve member includes a directional head mounted on a movable pivot arm fulcrumed to a stationary support in said reservoir portion, and conduit'means coact ing with" said valve member for selective transmission eluding an entry port, said pivot arm comprising a plate-like member pivoted at laterally spaced points to I said stationary horizontally oriented plate, and an electrical force coil coupled to said pivot arm 'for driving said valve'head to selectively control the flow of liquid from said scoop means to'said conduit means, said plate-like'member being movable by said force coil in a generally vertical plane for causing coaction of said head with one or the other of said entry ports of sai conduit means.

14. An actuator in accordance with claim 6 wherein saidpower unit for driving said casing is a reversible motor whereby said casing can be'driven in either ro-' tary direction, and saidscoop means in said casing comprises plural oppositely directed scoops for scooping liquid from the rotating liquid ring in saidcasing either rotary direction of said casing.

15. An actuator in accordance with claim 1 wherein said scoop means comprises an elongated tubular-like member having an inlet port therein, said member being stationary with respect to said casing and said inlet port facing in a direction generally opposite the direction of rotation of said casing.

16. An actuator in accordance with claim 15 wherein said scoop member has a plurality of other intake ports spaced along the lengthwise extent thereof, said other intake ports having valve means coacting therewith for normally maintaining said other ports closed in the rest condition of said casing but permitting opening of said; other ports for entry ofliquid therein from the rotating" liquid ring in said casing during rotation of the latter,

the last mentioned valve means being adapted to close' said other intake ports upon predetermined build-up in said scoop member.

17. actuator in accordance with claim 1 wherein said last mentioned means comprises a vertically oripressure ented multiple tube-like member detachably secured to the underside of said casing, said member having generallyjvertically extending passageway means therein communicating the interior of the casing with said reservoir for-ingress of liquid from the reservoir'to the in"- terior of the casing, and said self-priming'means including at least one vertically extending passageway in said member which projects laterally of said member and terminates in a hollow stem portion, said laterally extending stern portion creating a vacuum for causing the air in the casing to be withdrawn therefrom and permitting the casing to receive liquid from the reservoir portion for establishment of said liquid ring.

18. An actuator in accordance with claim 8 including an electric motor operatively coupled to the first mentioned means and comprising said power means, said valve member being movable from a hold position wherein pressurized liquid from said scoop means to the hydraulic powered control mechanism is cut off to 

1. In a hydraulic actuator comprising a reservoir portion for storing actuating liquid, a bowl-type pump including a rotary casing adapted for receiving actuating liquid therein disposed above said reservoir portion, said casing being rotatable about a generally vertical axis and including means adapted for coupling to power means for rotating said casing to produce a rotating liquid ring of the actuating fluid in said casing, scoop means disposed interiorly of said casing for removing liquid from the rotating liquid ring during rotation of said casing, means coacting with said scoop means for transmission of the liquid from said scoop means to a hydraulic powered control mechanism, means coacting with said casing and extending downwardly therefrom into said reservoir portion for supplying liquid from the reservoir portion into said casing for forming said liquid ring, the last mentioned means including means for exhausting air from said casing during rotation thereof and providing for selfpriming of said pump.
 2. An actuator in accordance with claim 1 wherein said last mentioned means is circular in horizontal cross section and is detachably attached to said casing.
 3. An actuator in accordance with claim 1 wherein said last mentioned means is in the form of an inverted truncated conical-like member secured to said casing axially thereof, said member comprising passageway means therein communicating the interior of said casing with said reservoir portion for passage of liquid from said reservoir portion to said casing during rotation of the latter, said priming means comprising other passageway means in said member including a laterally extending opening in said member adapted to open into said reservoir portion below the surface of the actuating liquid therein, said lateral opening communicating the interior of said casing via the last mentioned passageway means with said reservoir portion to permit egress of air from said casing during initial rotation of the latter.
 4. An actuator in accordance with claim 1 wherein said last mentioned means comprises an elongated member secured to the underside of said casing substantially axially thereof and rotatable therewith, said member having passageway means therein extending generally lengthwise thereof from the underside thereof into communication with the interior of said casing, for the movement of actuating liquid from said reservoir portion upwardly into said passageway means and thence into the casing upon rotation thereof, said priming means comprising other passageway means in said member extending from communication with the casing downwardly to open laterally of said member and adapted to open below the level of the actuating liquid in said reservoir portion, whereby air in said casing will be initially discharged through the last mentioned passageway means during initial rotation of said casing to permit actuating liquid to be drawn from said reservoir portion through the first mentioned passageway means in said member into said casing to form the rotating liquid ring.
 5. An actuator in accordance with claim 4 including stationary means coacting with the underside of said member, said stationary means comprising a generally horizontally oriented plate mounted in said reservoir portion and engaging the underside of said member, said plate having an opening therein directly communicating the first mentioned passageway means with the area of said reservoir portion disposed below said plate.
 6. An actuator in accordance with claim 1 including a power unit operatively coupled to said casing for causing rotation thereof, and means mounting said power unit above said casing.
 7. An actuator in accordance with claim 1 wherein said priming means includes a hollow stem projecting laterally of said last mentioned means for creating a vacuum during rotation of said casing and last mentioned means for initially drawing air from said casing into said reservoir portion during rotation of said casing.
 8. An actuator in accordance with claim 1 wherein said means coacting with said scoop means comprises a movable valve member operable for directing liquid from said scoop means to a predetermined transmission path to the hydraulic power control mechanism.
 9. An actuator in accordance with claim 8 wherein said valve member includes a directional head mounted on a movable pivot arm fulcrumed to a stationary support in said reservoir portion, and conduit means coacting with said valve member for selective transmission of liquid from said scoop means to and from said hydraulic powered control mechanism.
 10. An actuator in accordance with claim 9 wherein said conduit means is disposed in said reservoir portion, power means coupled to said pivot arm for driving said valve head in a predetermined direction to selectively control the flow of liquid from said scoop means to said conduit means, and feedback means coacting with said valve member and with said hydraulic powered control mechanism, for maintaining stability in the operation of said valve member.
 11. An actuator in accordance with claim 10 wherein the last mentioned power means comprises an electrical force coil.
 12. An actuator in accordance with claim 9 wherein said stationary support includes a generally horizontally oriented plate disposed in said reservoir portion above said valve member for protecting the valve member and associated entry port of said conduit means from foaming of liquid in said reservoir portion.
 13. An actuator in accordance with claim 12 wherein said conduit means comprises a pair of separate conduits connecting said valve member with the hydraulic powered control mechanism, each of said conduits including an entry port, said pivot arm comprising a plate-like member pivoted at laterally spaced points to said stationary horizontally oriented plate, and an electrical force coil coupled to said pivot arm for driving said valve head to selectively control the flow of liquid from said scoop means to said conduit means, said plate-like member being movable by said force coil in a generally vertical plane for causing coaction of said head with one or the other of said entry ports of said conduit means.
 14. An actuator in accordance with claim 6 wherein said power unit for driving said casing is a reversible motor whereby said casing can be driven in either rotary direction, and said scoop means in said casing comprises plural oppositely directed scoops for scooping liquid from the rotating liquid ring in said casing in either rotary direction of said casing.
 15. An actuator in accordance with claim 1 wherein said scoop means comprises an elongated tubular-like member having an inlet port therein, said member being stationary with respect to said casing and said inlet port facing in a direction generally opposite the direction of rotation of said casing.
 16. An actuator in accordance with claim 15 wherein said scoop member has a plurality of other intake ports spaced along the lengthwise extent thereof, said other intake ports having valve means coacting therewith for normally maintaining said other ports closed in the rest condition of said casing but permitting opening of said other ports for entry of liquid therein from the rotating liquid ring in said casing during rotation of the latter, the last mentioned valve means being adapted to close said other intake ports upon predetermined pressure build-up in said scoop member.
 17. An actuator in accordance with claim 1 whereiN said last mentioned means comprises a vertically oriented multiple tube-like member detachably secured to the underside of said casing, said member having generally vertically extending passageway means therein communicating the interior of the casing with said reservoir for ingress of liquid from the reservoir to the interior of the casing, and said self-priming means including at least one vertically extending passageway in said member which projects laterally of said member and terminates in a hollow stem portion, said laterally extending stem portion creating a vacuum for causing the air in the casing to be withdrawn therefrom and permitting the casing to receive liquid from the reservoir portion for establishment of said liquid ring.
 18. An actuator in accordance with claim 8 including an electric motor operatively coupled to the first mentioned means and comprising said power means, said valve member being movable from a hold position wherein pressurized liquid from said scoop means to the hydraulic powered control mechanism is cut off to an energizing position wherein pressurized liquid from said scoop means is directed to the hydraulic powered control means, said electric motor in said hold position of said valve member being operative to draw less power from the supply line.
 19. An actuator in accordance with claim 8 including surge reservoir means coacting with said scoop means for storing pressurized liquid from said scoop means therein, when said valve member is in predetermined position. 